Headache is a common complaint in the emergency department (ED). In order to examine headache work-ups and diagnoses across the USA, we queried a representative sample of adult ED visits (the National Hospital Ambulatory Medical Care Survey) for the years 1992-2001. Headache accounted for 2.1 million ED visits per year (2.2% of visits). Of the 14% of patients who underwent neuroimaging, 5.5% received a pathological diagnosis. Of the 2% of patients who underwent lumbar puncture, 11% received a pathological diagnosis. On multivariable analysis, a decreased rate of imaging was noted for patients without private insurance [odds ratio (OR) 0.61, confidence interval (CI) 0.44, 0.86] and for those presenting off-hours (OR 0.55, CI 0.39, 0.77). Patients over 50 were more likely to receive a pathological diagnosis (OR 3.3, CI 1.2, 9.3). In conclusion, clinicians should ensure that appropriate work-ups are performed regardless of presentation time or insurance status, and be vigilant in the evaluation of older patients.